The present invention relates to a processing apparatus such as a wafer cleaning apparatus for cleaning, e.g., a semiconductor wafer.
In the semiconductor manufacturing process, cleaning of a semiconductor wafer (to be simply referred to as a wafer hereinafter), e.g., removal of fine particles, removal of metal contamination, removal of an oxide film, and the like must be performed. In the cleaning process to remove fine particles, liquid phase cleaning using an NH.sub.4 /H.sub.2 O.sub.2 /H.sub.2 O solution mixture (to be referred to as APM hereinafter) is generally performed. In the cleaning process to remove metal contamination, liquid phase cleaning using an HCl/H.sub.2 O.sub.2 /H.sub.2 O solution mixture (to be referred to as HPM hereinafter) is generally performed. In the cleaning process to remove an oxide film, liquid phase cleaning using an HF/H.sub.2 O solution mixture (to be referred to as DHF hereinafter) is generally performed.
Recently, while single wafer processing of each process has been advanced along with an increase in wafer diameter, single wafer processing has also progressed in this cleaning process. For example, one wafer cleaning apparatus for single wafer processing is constituted by arranging processing chambers for performing APM cleaning, HPM cleaning, and DHM cleaning along a wafer convey path for conveying a wafer, and movably arranging, on the wafer convey path, a wafer conveyor for transferring the wafer between these processing chambers.
The respective processing chambers have almost the same arrangement. FIG. 1 shows an example of the schematic arrangement of the processing chamber.
As shown in FIG. 1, a holding member 101 for rotatably holding a wafer W, and an injection nozzle 102 for injecting a predetermined cleaning solution, e.g., the NH.sub.4 /H.sub.2 O.sub.2 /H.sub.2 O solution mixture for APM cleaning, to the surface of the wafer W held and rotated by the holding member 101 are arranged in a closed processing chamber 100. An openable window portion 103 for transferring the wafer W is formed in the front surface of the processing chamber 100 on the wafer convey path side. A wafer conveyor 104 movably arranged on the wafer convey path transfers the wafer W to be cleaned via the window portion 103.
In this arrangement of the processing chamber 100, if the atmosphere in the processing chamber 100, e.g., the NH.sub.4 gas for APM cleaning leaks outside the processing chamber, e.g., to the wafer convey path side, the gas adversely affects a wafer on the wafer convey path. For this reason, such leakage must be avoided. Therefore, an inlet port for introducing the outer atmosphere is formed at a predetermined position of the processing chamber 100 to evacuate the interior of the processing chamber and set the interior of the processing chamber at a negative pressure.
Even if the exhaust means is arranged in the processing chamber of the wafer cleaning apparatus in the above manner, when the window portion 103 is opened to allow transfer of the wafer W, the negative pressure set inside the processing chamber may weaken, and the atmosphere in the processing chamber may leak outside via the window portion 103. When the exhaust means fails in exhaust due to any cause, the atmosphere in the processing chamber may leak outside via the above-described inlet portion.
In this wafer cleaning apparatus, one wafer is loaded into the unit, and cleaned with a cleaning solution such as the APM, the HPM, or the DHF, and then with a rinsing solution such as deionized water (DIW). The cleaning and rinsing solutions used and the like are generally discharged as the waste.
Of such cleaning and rinsing solutions, particularly the cleaning solution is very expensive. When the above single wafer processing is not performed, a large amount of cleaning solution is consumed, resulting in a high running cost. In the single-wafer cleaning apparatus, a cleaning solution bath for storing the cleaning bath is bulky, and the space cost is high.